Officials yesterday showed off the spanking new $1 billion Barclays Center during a ceremonial ribbon cutting at the Nets’ 18,200-seat arena.

Sporting a rust-colored, metallic façade, the 675,000-square-foot building consists of 12,000 unique panels fabricated from 600 tons of weathered steel. It’s exterior includes tree-lined seating areas, a subway entrance covered with plantings and a pedestrian-friendly view of the Barclays Center scoreboard through the arena’s glass doors.

The arena also has a sense of history. Near the main entrance at Flatbush and Atlantic avenues is a white flagpole from Ebbets Field, where the Dodgers played before abandoning Brooklyn for Los Angeles after the 1957 season.

Perhaps the arena’s most eye-grabbing feature is a huge canopy at the main entrance with an oval window in its center — called an “Oculus.” It extends out 117 feet and hovers 30 feet above a public plaza. A video screen that will display everything from game highlights to art installations wraps the perimeter of the Oculus.

After heading through the main gate, patrons will step into a 9,000-square-foot glass-enclosed atrium offering spectacular views of the arena bowl and scoreboard. But they’ll also have to step through the first-ever full-time metal detectors at a Big Apple sports venue.

After flipping a light switch to show off the Nets’ herringbone-design court with its large black “B” at midcourt, developer Bruce Ratner said he expects to break ground Dec. 18 on the first residential tower for his long-stalled Atlantic Yards project nearby that the arena is the centerpiece of. It’ll have 350 units — half set aside as affordable housing — and rise at Dean Street and Flatbush Avenue. The remaining planned 15 residential and commercial towers are on hold due to the slumping economy.

The arena opens Sept. 28 with a series of eight concerts by rap mogul/Nets part-owner Jay-Z, while the Nets open this season at home on Nov. 1 against the rival Knicks.

The arena has 101 luxury suites, including 11 Jay-Z-designed special suites called “The Vault” that cost $550,000 a year and are stocked with high-end champagne. The remaining suites average more than $260,000 a year to lease.

And while most arenas usually rely on corporations to supply food, the Barclays Center food experience will offer the best of Brooklyn. It’ll include brisket hot dogs by Brooklyn Bangers, pizza by L & B Spumoni Gardens, barbecue brisket and pork sandwiches by Fatty ‘Cue, franks and fries by Nathan’s Famous and – of course — cheesecake by Junior’s.

Nets majority owner Mikhail Prokhorov, who saw the finished arena for the first time yesterday, compared its opening to the “opening of the Brooklyn Bridge.”

“Today’s opening is a defining moment in the history of Brooklyn,” the Russian billionaire said.

After the Atlantic Yards project was granted state approval in Dec. 2006, the arena was supposed to break ground a month later, open by 2009 and the rest of Atlantic Yards was supposed to be done by 2017. However the development plan was nearly killed several times thanks to lawsuits and a national credit crunch.

The arena only broke ground after Ratner in Sept. 2009 sold Prokhorov 80 percent interest in the Nets and 45 percent interest in the arena for $223 million plus an agreement to pick up $60 million in debt.

“It took us a little longer to get here, but this arena has exceeded any of our expectations,” said Nets/Barclays Center CEO Brett Yormark.